I'm trying to include a date flag "date -R" in a bash script to use RFC 2822 and the script works fine in macOS 10.12 but not in Mac OS X 10.11. I get an illegal option.
I checked the man pages for date and the date -R flag seems to be available in 10.12 but not in 10.11 even though both systems are running the same version of bash.
Any idea of why there would be a difference or any work arounds? We're testing -u to use a universal time code but my main concern is non-english unicode characters.
We're trying to to convert non-English Unicode characters in CSV files and timestamps keep showing up as issues.